It is common in the construction industry to employ a machine that has a front and rear frame that are pivotally mounted to one another for relative movement about a pivot axis. Each frame defines a hitch portion in the area of articulation and each hitch portion is pivotally mounted to one another about a common axis. Typically the hitch will include an upper and lower hitch portion, each of which is pinned together by a hitch pin assembly. It is common practice to utilize upper and lower pin assemblies that are of different construction to accommodate the various types of loading transmitted between the two frames as a result of machine operation. While both pin assemblies must accommodate relative rotation between the frame members, the lower pin assembly is typically designed to accommodate the bulk of the radial and thrust loading that occurs between the frame members.
The design of the pin assemblies included in the lower hitch portion has typically included a pin member that is positioned in aligned bores between a pair of frame members. One frame member typically defines a single plate that is positioned between a pair of spaced apart plates defined by the other of the frame members. A bearing assembly is mounted in the single plate and a pair of spacers are positioned on opposite sides thereof and extend outwardly to contact each of the plates of the second frame. A first set of bolts mounts a lock plate to the second frame member to capture the spacers and the bearing assembly between spaced plates. A pin assembly is positioned within the aligned bores and has a first end portion that engages one of the spaced plates and a second end portion that is secured to the lock plate by a second plurality of bolts. In these designs, in order to accommodate manufacturing tolerances of the various components, the length of the pin is such that it stops short of the lock plate and creates a space therebetween.
During the operation of the machine, and subsequent transfer of forces between the two frames, the various components in the pin assembly are caused to flex with respect to one another. This flexing is accentuated in the lower pin assembly due to the space that exists between the pin and the lock plate. As a result, the mounting bolts that secure the lock plate to the pin and the second frame tend to loosen. This in turn, results in the loss of the bolts and the failure of the hitch pin assembly.
The present invention is directed to overcoming one or more of the problems as set forth above.